1992 3.0 cold start issues (in Alaska)

[SteveinAlaska]

Hello to all after an extended absence. Surviving Covid & whatever else is out there. Anyway, finished out 2019 and went into 2020 expecting to spend some money on my workhorse, everyday driver. Covid hit & the truck sat for almost 4 months. Did not get out to drive it until warm weather (mid May 2020) Got into cold weather (October 2020) and it went belly up on me. Spring 2021 (again May) finally diagnosed and replaced ORIGINAL distributor cap,rotor and plug wires along with the damaged starter as a result of motor back firing,etc. As of today I have put the truck in a reputable local shop and they have replaced the mass airflow sensor along with oil changes & other misc. fixes. At this point I have been told that are going through a "wet cycling" process to reset the computer/black box/ ecm module. This I can understand as I retired myself from working as an auto tech about 1980 when those little black boxes came on the scene. QUESTION TO THE GROUP ...........Given that this is a 1992 model with 114,000 miles and almost 30 years old, could I anticipate replacing the ecm module or whatever black box is in this rig? I on more than one occasion let the battery run down because I left the interior light on (blame that one on old age) & in the course of use also disconnecting the battery (starter replacement). As I write this we are going from -40f to zero degree weather in the next couple of days. Appreciate any thoughts, suggestions on this.

 

[rusty ol ranger]

If you replaced the cap and rotor then you dont have a 4.0. All 4.0s were EDIS (electronic distributorless ignition system).

Also yes....its very possible the ECM is bad but there could be a million other things to from sensors to wireing to mechanical.

What exactly was the truck doing when it went "belly up"? Wouldnt crank? Wouldnt fire? Wouldnt stay running? Describe the symptoms and we can help you much more.

 

[PetroleumJunkie412]

Move to Mississippi.

Problem solved.

 

[Roert42]

Move to Mississippi.

Problem solved.

 

[SteveinAlaska]

If you replaced the cap and rotor then you dont have a 4.0. All 4.0s were EDIS (electronic distributorless ignition system).

Also yes....its very possible the ECM is bad but there could be a million other things to from sensors to wireing to mechanical.

What exactly was the truck doing when it went "belly up"? Wouldnt crank? Wouldnt fire? Wouldnt stay running? Describe the symptoms and we can help you much more.

WHOOPS!! That's what happens when it's late at night and you post in the wrong thread. Will move to the 3.0 thread now

 

[sgtsandman]

Thread title edited and moved to the 3.0 sub forum.

 

[RonD]

ECM(PCM) does have 2 or 3 "barrel" capacitors that can fail after 20+ years, easy and cheap to replace these, just as preventative maintenance or if there are running issue

Its very hard to ignite gasoline with a spark as the temp drops
In fact a spark can't ignite liquid gasoline at all, movie myth, lol

Only gasoline VAPOR can be ignited by a spark, and the colder gasoline gets the less vapor there is, i.e. you can smell gasoline in the summer but not in the winter, because there is less vapor

To start a cold gasoline engine each cylinder needs 30% vapor as a minimum for a GOOD spark to ignite it
If cold gasoline is only 10% vapor then you need 3 times as much as warm gasoline at 30% vapor to get good ignition from a spark

That's what a CHOKE was/is for, it closed off the top of a carburetor, so it sucked in less air and MORE fuel, to get more vapor if gasoline was cold
Fuel injection doesn't change the physics of gasoline being ignited by a spark
But it changes the method of how to get more Vapor
All fuel injected engines have an ECT(engine coolant temp) sensor, this is different than the dash Temp gauge sender
The ECT sensor tells the computer how cold the engine is so how much extra fuel to add(choke) to get to the 30% vapor point

Spark
Wider gaps on spark plugs are better for cold starts and lower RPM driving
Narrower gaps are better for high RPMs(racing)
The recommend gap is a compromise between these two things
So you gap YOUR spark plugs to suit YOUR needs

Spark and battery
Car batteries needs to be 12.3volt to 12.8volt
Under 12.3 volt is a done battery in most cases, only at 50% capacity

When starter motor is on the battery volts drop by 1.5 to 2.5volts, the colder it is the bigger the drop
The spark system works by multiplying the battery volts to higher spark voltage
So when cranking over the engine the battery volts are lower, under 10volts, so spark voltage is also lower
Its a double whammy, low vapor and low spark voltage on cold starts

So Battery condition is very important for cold starts, also for cranking speed, the faster the engine spins the more friction and HEAT it generates in the cylinders, this HEAT warms up the incoming liquid gasoline which produces higher vapor levels that a weak spark may ignite

Quick Start(ether) is often used to start cold engines
Ether is a vapor at very low temps, and its combustible by spark
So a spray of ether into a cold engine will get cylinders to fire, which WARMS them up instantly, so the incoming gasoline can vaporize faster for continued running without the ether


Diesel engines are even worse in cold climates because they use HEAT ignition not spark
They have high compression ratios to HEAT the diesel in a cylinder so it self ignites because of the high temp
Glow plugs are used to pre-heat the cylinders, but it can take awhile and lots of Battery juice to warm up the cylinders, and even more battery juice to turn over a high compression engine, lol